1. Field of the Invention
The present invention relates to a seat for use in an automobile, airplane and house, and, more particularly, to a seat having decorative welts in the top cover member thereof which forms the surface of the seat.
2. Description of the Prior Art
Conventionally, seat welts are generally interposed between seat reinforcement or top cover member and gore portions, that is, the sewn portions thereof, and are then sewn there by a sewing machine.
This means that mounting of the welts requires skill, resulting in the high cost of the seat. For this reason, There are signs of development of new methods for attaching the welts without using the machine sewing.
For example, in Japanese Patent Publication No. 95089 of 1984, there is disclosed a method in which upper and lower molds are used to roll a welt core into one end of a gore portion or a top cover member and the welt core is welded by means of high-frequency waves to form a welt.
According to this method, there is eliminated a step of the above-mentioned machine-sewing. The method, however, involves a special operation that, after the roll-in of the welt core, the portions of the gore and top cover members where the welt core is interposed must be mounted in substantially 90 degrees. Also, in this method, the gore portions and the top cover member are formed of different members, respectively.
Also, according to another method which is disclosed in Japanese Patent Publication No. 156372 of 1984, a welt core is inserted into the projection portion of a vacuum-formed trim cover assembly, the undiluted solution of foam synthetic resin such as urethane foam is thereafter injected into the interior of the trim cover assembly, and it is then foamed and cured to unite the welt core, trim cover assembly and a foam cushion member into one so as to form a welt.
In this case, the machine-sewing operation is eliminated and also it becomes easier to form the welt since the welt is not interposed as in the previously-described prior art but it is formed integrally with the trim cover assembly and the foam cushion member. However, this method requires special equipment for vacuum-forming the trim cover assembly as well as the welt. Also, due to the integral formation by means of the foaming and curing operation, a seat produced using this method becomes large in size, is limited in shape, and is thus hard to adapt itself to circumstances.